A first alpha version of a Qt implementation for the Android mobile operating system has been announced by Romanian software developer Bogdan Vatra. Since Nokia in co-operation with Microsoft have announced that it does not intend to develop a Windows Phone variant of the GUI framework, Qt for Android represents the only remaining route/platfrom to providing mobile phone apps developed using Qt.

Qt on Mac is really really good and it uses the native rendering system (Cocoa) to draw its widgets, so, your "Qt on Mac is a disaster" is just speculation. If the developer was not able to create a nice native UI on mac using Qt, is not Qt's fault. Look at Qt Creator on the Mac, it is beautiful and looks very very native.

Easy now. Qt on mac is rather good, but i wouldn't call it REALLY good. Language bindings are tricky, and at times you've got to compile qt yourself to have the right flavour for you particular binding.
It does draw native widgets, but only a subset of what cocoa does natively, and you really have to go out of your way to make it look and behave like people (well, mac people) expect a quality OSX app to do.
Interface designer on the mac is a prime example on how great an qt app may looks with KDE, and how poor it looks (and behaves) in OSX.

What i'm saying is that while it's true qt does draw native widgets in OSX, at times it's as rough as google translate can be when doing word for word translations. Details get lost in the process.
My own experience tell me that you have to tweak even qt gui code to fit well with the OS/DE your targeting, at least with desktop applications.